Surfactant Protein D Is Altered in Experimental Malaria-Associated Acute Lung InjuryAcute Respiratory Distress Syndrome

Abstract EN

Surfactant protein D (SP-D) is in the collectin family of C-type lectins and plays an important role in the regulation of inflammation and the innate immune defense against pathogens.

This protein has been proposed as a biomarker for acute lung injury.

However, the expression of SP-D in the lung and the circulating levels of SP-D during malaria infection have received limited attention.

Therefore, the aim of this study was to determine the location and expression of the SP-D protein in lung tissue and to measure the plasma level of SP-D in experimental malaria-associated acute lung injury/acute respiratory distress syndrome (ALI/ARDS).

Malaria-infected mice induced by Plasmodium berghei ANKA were classified into two groups, namely, the ALI/ARDS and non-ALI/ARDS groups, according to lung histopathology.

The lungs of uninfected mice were used as a control group.

The location and expression of SP-D in the lung tissues were investigated by immunohistochemical staining and Western blot analysis.

In addition, the level of SP-D in plasma and lung homogenate was measured by an enzyme-linked immunosorbent assay.

Immunohistochemical staining of SP-D was significantly increased in the lung tissues of the malaria-infected mice in the ALI/ARDS group compared with that in the malaria-infected mice in the non-ALI/ARDS group and the mice in the control group (p < 0.05).

The levels of SP-D in the plasma and lung homogenate were significantly increased in the malaria-infected mice in the ALI/ARDS group compared with those in the malaria-infected mice in the non-ALI/ARDS group and the mice in the control group (p < 0.05).

There was a significant positive correlation between SP-D in the plasma and SP-D in the lung homogenate (rs = 0.900, p = 0.037).

In conclusion, this study demonstrated increased expression levels of SP-D in the lung tissue and high levels of plasma SP-D in the malaria-infected mice with ALI/ARDS compared with those in the mice in the other groups.

The current study supports that the elevation of the plasma SP-D level may provide useful biological confirmation of the diagnosis of ALI/ARDS during malaria infection.